Existing apparatus and methods for repair of damaged vehicle glass involve subjecting a space around the area of damage to a partial vacuum to allow satisfactory penetration of an optically compatible resin into the area of damage, and extraction of air from the resin itself, curing the resin once the damaged area has been filled, and finishing the repair by removing excess cured resin and polishing the surface of the previously damaged area.
Problems which arise concern adequate degassing of both the damaged area and the resin. For example, the apparatus described in U.S. Pat. No. 4,193,005 and U.S. Pat. No. 4,385,015 has a suction cup connected to a vacuum pump. A tube extends through the suction cup and seals against the surface of the glass around the flaw to be repaired. The inside of the tube communicates through a radial vacuum port with the space inside the suction cup. Resin is introduced into the tube and a piston is then introduced into the tube, at which time the vacuum pump acts on the flaw and the resin in the flaw to degas both the resin and the flaw. Degasification in this way needs more time and is less effective, since gas from the flaw has to leave through the resin.
U.S. Pat. No. 4,776,780 describes a hand-operated suction cup through which a passage is provided for receiving repair liquid, such as a curable resin. The passage seals against the surface of the glass when a vacuum is applied to the suction cup, and the passage is completely isolated then from the suction cup interior. Resin is introduced into the passage and a piston is moved up and down in the passage to evacuate or pressurising the space within the passage. This apparatus encounters similar degassing problems described above.